OpenFlow is a southbound protocol in software defined networking (SDN) architectures. In a classical router or switch (e.g., an Ethernet switch), the fast packet forwarding (data path) and the high level routing decisions (control path) occur on the same device. An OpenFlow switch separates these two functions. The data path portion still resides on the switch, while high-level routing decisions are moved to a separate controller, typically a standard server. The OpenFlow switch and controller communicate via the OpenFlow protocol, which defines messages, such as packet-received, send-packet-out, modify-forwarding-table, and get-stats.
In addition to the OpenFlow controller, OpenFlow architecture includes OpenFlow agents. OpenFlow agents run on network devices, e.g., Ethernet switches. In an OpenFlow based SDN architecture, OpenFlow devices must be managed only by the OpenFlow controller as a “datapath” using a flow based view of traffic, i.e., the switch must not export its own interface for configuration and management. Because the OpenFlow controller does not recognize “flow instructions” for configuring properties of the OpenFlow devices, the properties of an OpenFlow device that would allow an OpenFlow controller to communication with the device are configured using an OpenFlow configuration protocol by a separate configuration agent. Accordingly, the software support for the OpenFlow configuration protocol is deployed and maintained in the switch network fabric.